Copying a document on a copy system typically involves placing a document (either manually or automatically) in contact with a copy surface. Because most copy machines accommodate different size documents, the copy surface is usually larger than a typical 8.5 inch.times.11 inch (215.9 mm.times.279.4 mm) piece of paper. As a result of the large copy surface, documents can be placed on the copy surface in positions that do not correspond to the particular location required for copying, which will be referred to herein as the "copy area" or "print area." Documents located in the wrong position result in unacceptable copies that are usually discarded, wasting time and resources.
Properly locating a document on a copy surface is further complicated when features such as magnification or reduction are utilized. When magnification or reduction features are utilized, it is difficult to determine exactly how the document fits within the actual copy area, and it is difficult to determine how images on the document will appear on the copy.
In order to determine the appearance of a document copy before a copy is actually generated, it would be advantageous to have a copy system that enables document previewing. In conventional photocopiers, document copying is accomplished by illuminating a document and then directing reflected light from the document onto a photosensitive belt or platen. Changes in electrical charge on the photosensitive belt or platen are then utilized to transfer toner to a new piece of paper. While conventional copiers work well for their intended purpose, the copiers do not include sensing hardware that can be easily utilized for document previewing.
In addition to conventional copiers, copy systems have been developed that utilize electronic imaging techniques to copy images from documents. Systems utilizing electronic imaging have been equipped with document previewing capability. Known copy systems with document previewing capability are disclosed in U.S. Pat. No. 4,656,524 entitled "Electronic Imaging Copier," issued to Norris et al., and U.S. Pat. No. 4,656,525 entitled "Electronic Imaging Copier," issued to Norris. Both copiers of Norris utilize a photo responsive device such as a linear charged coupled device (CCD) array to capture an electronic image of the target document. The electronic image is utilized to print a copy of the target document. The electronic image is captured by passing the linear CCD array by the document in a line-by-line manner.
Previewing a document with the Norris copiers involves scanning the document with a linear CCD array to create electronic image data and then displaying the electronic image data on a display device. The Norris copiers utilize the same scanning hardware for document previewing as is used for document copying. While the previewing feature of Norris works well for its intended purpose, previewing a document utilizing the same scanning hardware as is used for document copying requires a line-by-line scan of the document. The mechanical movements required for line-by-line scanning are time consuming and prevent real-time previewing of the target document.
Known preview systems have also been applied in image scanners that are used to create an electronic copy of a document. For example, an image scanner that includes a preview system is disclosed in U.S. Pat. No. 4,837,635 entitled "A Scanning System in which a Portion of a Preview Scan Image of a Picture Displaced on a Screen is Selected and a Corresponding Portion of the Picture is Scanned in a Final Scan," issued to Santos and assigned to the assignee of the present invention. In Santos, the scanner can perform either a preview scan or a final scan. The preview scan is simply a lower resolution version of the final scan. Again, the same scanner hardware is utilized to perform the preview scan or the final scan. Whether the scanner is performing a preview scan or a final scan, the scanner hardware must sweep across the document in a line-by-line manner to capture the electronic image data. Although the preview system of Santos works well for its intended purpose, the time required to scan a document limits the ability to provide real-time previewing.
As a result of the drawbacks regarding prior art preview systems, what is needed is a preview system that can display a document located on a copy surface without utilizing the document copy hardware, and what is needed is a preview system that can display a document in real-time.